The regiments of the Lyran Regulars were prone to being disbanded and reactivated as needed; each time a regiment was reactivated, it would be populated with a mix of re-enlisted veterans and fresh recruits, before being assigned to a garrison posting to free up a line regiment for active service. During peacetime, the Regulars would then disband down to a much smaller size as a brigade, awaiting the next time they would be called on. The Fourth were an active regiment in 2765, stationed on Elume, and were responsible for causing a stir within the Lyran Commonwealth Armed Forces. The focus of this attention was ColonelMichelle Eanes, the Commanding Officer; Colonel Eanes had married one of her subordinate officers, HauptmannLiza Stansfield. The LCAF had responded by attempting to post Stansfield to another command, but Stansfield was suing to have the posting overturned, citing that military regulations allowed for fraternization between officers, only forbidding relationships where one officer was reporting directly to another. The LCAF High Command responded by making life as difficult as possible for the 4th to put as much pressure on the two officers as possible, while their case worked its way through the Commonwealth's military courts.[4]

After the Fourth Succession War, the unit would see the worlds they had helped conquer for their home province of the Tamar Pact given away to the newly formed Free Rasalhague Republic in 3033. A year later these hard-won worlds would come under attack by rogue Draconis Combine regiments attempting to retake the Republic for House Kurita.[7] By this time, the unit has been transferred to Blue Diamond as its new garrison world. Without a break in fighting, the unit took advantage of the situation and conducted a series of raids against the Draconis Combine as a means to vent their frustration forcing the House Steiner to give up worlds for formation of the Republic.[8]

The Regulars were assigned as part of the attack forces used in the FedCom's invasion of the Draconis Combine in the War of 3039.

In the first wave of the conflict, the Regulars were part of the assault force assigned to attack Konstance. They arrived in April of 3039 with 4thCrucis Lancers and the mercenary force, Mobile Fire to take the system. On the CO2 laden world, due to mechanical problems was the 22ndDieron Regulars. The FedCom expedition planned to conduct a two-prong invasion of the planet, taking the capital of Ishtalla and important sites on the continent of Epigaus. The Regulars were assigned to Task Force Hope, the Task Force commander Leftnant-General Michael Bradbury directing the Task Force to land 40 kilometers outside the city of Lazarus Bay on Epigaus.

The Regulars moved into the city where they found a battalion of the 22nd Dieron Regulars with conventional Armor forces dug in waiting for them. The Dieron 'Mechs struck first, conducting a series of quick flanking attacks. The 4th Lyran Regulars countered with their own raids. These fast attacks from both sides would make the battlefield quick and ever changing situation. The quick-paced battle quickly used up the Task Force's allotment of spare parts, but the 4th and its mercenary allies gained control of the city and its port facilities. After securing the city, the Regulars' allies in Ishtalla would note only token resistance in comparison to the Regulars' fight for Lazarus Bay, leaving the threat of remaining components of the 22nd Dieron on the loose. During their occupation of the city and its surroundings, the 4th and its allies would suffer from a series of strikes conducted against them by Dieron Regulars. The Combine troops had taken to using civilian submarine transports and using them to strike them with no means for the Regulars hit back. Tensions between the Regulars' leadership and that of the Crucis Lancers developed, with arguments over seniority. The High Command's ability to guide the War had been knocked out with the unsuccessful assassination attempt on General Nondi Steiner on Vega.

By August, the expedition had failed to convince High Command to dispatch reinforcements and naval assets to the planet to help hunt down the 22nd Dieron. On the 19th, Draconis Combine reinforcements in the form of the 3rd Dieron Regulars had arrived via a pirate point. Led by Tai-sho James Kurenal, who directed the 3rd Dieron to a landing zone south of Lazarus Bay. The 4th Lyran Regulars now faced a heavier force, but had hoped their lighter and faster machines would be able to outmaneuver the incoming Kuritan force. The 4th Lyran moved swiftly, surprising the incoming 3rd Dieron who were prepared to conduct a city assault. Two battalions of Lyran Regulars drove straight to the HQ of the 3rd Dieron; however due to earthworks erected to protect the Kurita infantry, this caused the fast-moving 'Mechs of the 4th Lyrans to slow down enough for the 3rd Dieron's command Company to take advantage of their maneuver. The Combine force led by Tai-sho Kurenal charged into the flank of the 4th Lyran's attack force with such velocity and venom that it caused the Lyrans' commander to retreat which then became a rout. The damage inflicted by the Kurita counter-attack left long-lasting psychological damage to the Lyran Regulars for decades to come. A company Kurita troops would cause two battalion of worth their numbers to withdraw in route, something they would refuse to believe a generation later.

Lt. General Bradley would order the Regulars to fall back to the Lazarus Bay. On September 3rd, the surviving elements of the 22nd Dieron Regulars combined forces with some of the 3rd Dieron to breach the Lyran's defenses of the city. Mobile Fire's 3rd Division's expertise with urban warfare proved enough to win them a string of successes against their Kurita invader's lack of experience in urban fighting. However shortly afterwards the Mobile Fire's commanding officer, Quinten Moore, was killed, leaving the Regular's commander with the decision to withdraw from the planet. He would order a retreat from the planet on September 5th, abandoning the 4th Crucis Lancers to their own devices due to his own bitterness over arguments seniority. Bradley would cause the Crucis Lancers to agree to parley and withdraw from Kontance in November.[9]

The 4th Lyran Regulars would be spared being deployed to the war front during the Clan Invasion. After the Battle of Tukayyid and its Truce in 3052, the FedCom High Command selected the Regulars among other units to conduct raids into the Clan Occupation Zones. The combat in these raids were high intensity, and 30 percent of the 4th 'Mech assets would be lost. The unit was considered so badly damaged that the Lyran High Command ordered it be deactivated while it was being rebuilt.[10][11] During its rebuilding and reactivation, the unit would come under the command of Colonel Chas Mohring, whom transferred from the 4th Deneb Light Cavalry. He would from his first day of taking command begin to teach the unit new tactics learned during his years with the 4th Deneb.

The unit had been considered hot bed for criticism of the Archon by 3062, though originally suspected due to the unit's ties with former Tamar Pact and its ruling family whom now controlled Skye. However, its criticism from its ranks was aimed towards their burning hatred for the Clans.

Neutral at start of the War, the unit would ultimately be drawn into the fight. The Regulars would join the 11th Arcturan Guards' Battle Group of Lyran Loyalist forces hunting down Victor Steiner-Davion. Task Forces now encumbered 4th Alliance Guards, Alarion and Carisle PTMs arrived on Thorin in August 7th, 3065 with reports suggesting the Prince was on world. The Regulars and rest of the task force moved to planet's capital of Ecol City. However both 244th Division and Outlands Legion repulsed the move to try to take the city. General Linda MacDonald's 11th Arcturan Guards' and Task Force's commander lead Regulars and it troops in a two week action against the Victor's ally troops. Regulars and the Task Force would continue to fight for control of Thorin until January 24th, 3066, where Victor Steiner-Davion would arrive on planet and pull his forces off planet. The moderately damaged Regulars would be left by Battle Group to garrison the planet for rest of the war. [12][13][14]

In February of 3068, Regulars were called by Marshal from their assigned on Thorin to participate in Operation Überschatten, the offensive against the Free Worlds League's attack of against Skye. During the course of the offensive, the Regulars would attack McAffe in May 20th, where the Ninth Regulan Hussars were garrisoning. However, the Regulars were led into an ambush which would inflict considerable damage to the unit. The 4th Regulars lost nearly a quarter of their troops withdrawing from the world. After action reports indicate that the Home Guard and two additional regiments of Marik Militia troops were on the world. The unit's staff was accused of incompetence and its command staff would be withdrawn from McAffe and assigned elsewhere.[15]

On July 2nd, Free Worlds League forces mounted a counter offensive against the Skye/Bolan Forces. The Regulars would be heavily damaged and rendered non-combat effective, with a third of its command captured by the League forces.[16][17] They spent the rest of the Jihad garrisoning Megrez.[15] In 3079 they were transferred to Ford.[15]

The 4th and 8th Lyran Regulars assaulted Epsilon in the Tamarind Abbey District. The Regulars faced the 34th Marik Militia which put up some resistance but eventually the LCAF force overwhelmed the battalion sized formation and forced them off world. They later fought for several months on Bella I in 3082 and eventually took that world as well. In 3085 they were still garrisoning Bella I.[18]

During the War of 3039, the Regulars would utilize its speed and try to out maneuver enemy force and try to hit them in their flanks or hit them with lightning fast strikes.[24]

By 3062, the unit's tactics would change after its reactivation and receiving a new commanding officer. The unit would utilize its attached Force's Hovercraft type Combat Vehicles forces to screen and scouts. It would augment its BattleMechs and heavier Combat Vehicles have them form Combined Arms subcommands to maneuver independently exploiting local terrain to their own advantage.[25]

4th Lyran Regulars (BattleMech Regiment)
CO:
Colonel Chas Mohring
Regulars Note: In 3062, the Regulars would be considered Regular skilled and listed with a Reliable loyalty rating while still stationed on Blue Diamond.[30] As of 3067, the unit strength would be 80%, while its noted being having regular skills and reliable loyalty rating.[31]

23rd Menkent Cavalry (ArmorRegiment)
CO:
Leutnant Colonel Devon Lestrade
Cavalry Notes: In 3062, the unit had been rated as Regulars, and Reliable along with rest of the regiment. In 3067 the Cavalry's strength would be up to 95%, with loyalty ratings of Regular and it was considered to be Reliable.[32]

Unit Note: In 3062, the Regulars (as whole) would be noted for taking a neutral status in growing during the reign of the Katrina Steiner-Davion leading to the Civil War. It had access to D rated Equipment this time period.

Devon Lestrade - The Armor/Tank Commander of the 4thh's attached combat vehicle regiment, he is a nephew of the traitorous late Duke of Summer, Aldo Lestrade. Unlike his late uncle, he would from all appearances does not possess a desire for intrigue. He is however politically astute and is among the number of officers who has a burning wish to destroy Clan Jade Falcon.[33] After the FedCom Civil War, he would be viewed as a patriotic individual refusing to be involved with the Free Skye movement. However this would estrange him from his family due to their ties with that rebel organization.[34]

From Field Manual: Lyran Alliance, the 4th Lyran Regulars' special abilities & benefits some stem from its Commanding officer Colonel Chas Mohring. The Regiment has been given the Banking Initiative ability.

Colonel Mohring's presence (Using Classic BattleTech RPG / MechWarrior 3 RPG rules) would be given any player character assigned to the unit +5 XP per month (in game time) for strictly Tactics and Strategy skills. While in a scenario, a player in command while using RPG character, can roll tactics skill check. If the player should win their roll, they would get the following benefits (Unless scenario's conditions allow and maps are randomly generated for it); The player may choose any four maps sheets when setting up the battle/scenario. They may choose their home edge and hide half of their force. Should the player fail their tactics check, the opposing player gain all advantages the controlling player would received.[35]

↑FedCom Civil War (sourcebook) p. 183 Civil War and DCMS Incursion Table - 4th Lyran Regulars' movement notes that it remained on planet after Victor left. The Fourth Alliance Guards would remain with the unit as part of Thorin's garrison force.

↑Jihad Hot Spots: 3070, p. 16-17 Timeline of the Jihad - Actual dates for 4th Lyran Regulars' assault of McAffe on May 20th and the date for when the unit was rendered non-combat effective by League forces.